CS0120 An object reference is required for the nonstatic field method or property foo

Question

Consider   namespace WindowsApplication1       public partial class Form1   Form               public Form1                         InitializeComponent                       private void button1 Click object sender  EventArgs e                          int   val     0  0               int val              if  textBox1 Text                                      MessageBox Show  Input any no                              else                               val   Convert ToInt32 textBox1 Text                   Thread ot1   new Thread new ParameterizedThreadStart SumData                    ot1 Start val                                    private static void ReadData object state                        System Windows Forms Application Run                       void setTextboxText int result                        if  this InvokeRequired                                this Invoke new IntDelegate SetTextboxTextSafe   new object     result                               else                               SetTextboxTextSafe result                                    void SetTextboxTextSafe int result                        label1 Text   result ToString                       private static void SumData object state                        int result                int   icount    int   state              int icount    int state               for  int i   icount  i  gt  0  i--                                result    i                  System Threading Thread Sleep 1000                             setTextboxText result                      delegate void IntDelegate int result            private void button2 Click object sender  EventArgs e                        Application Exit                        Why is this error occurring      An object reference is required for the nonstatic field  method  or property  WindowsApplication1 Form1 setTextboxText int

User · Answer

Your method must be static   static void setTextboxText int result        if  this InvokeRequired                this Invoke new IntDelegate SetTextboxTextSafe   new object     result                else               SetTextboxTextSafe result

User · Answer

Credit to  COOLGAMETUBE for tipping me off to what ended up working for me   His idea was good but I had a problem when Application SetCompatibleTextRenderingDefault was called after the form was already created   So with a little change  this is working for me    static class Program       public static Form1 form1       new Form1       Place this var out of the constructor           lt summary gt          The main entry point for the application           lt  summary gt       STAThread      static void Main                 Application EnableVisualStyles            Application SetCompatibleTextRenderingDefault false           Application Run form1   new Form1

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From my looking you give a null value to a textbox and return in a ToString   as it is a static method  You can replace it with  Convert ToString   that can enable null value

User · Answer

It looks like you are calling a non static member  a property or method  specifically setTextboxText  from a static method  specifically SumData    You will need to either    Make the called member static also   static void setTextboxText int result           Write static logic for setTextboxText           This may require a static singleton instance of Form1     Create an instance of Form1 within the calling method   private static void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             Form1 frm1   new Form1        frm1 setTextboxText result       Passing in an instance of Form1 would be an option also  Make the calling method a non-static instance method  of Form1    private void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             setTextboxText result        More info about this error can be found on MSDN

User · Answer

It looks like you are calling a non static member  a property or method  specifically setTextboxText  from a static method  specifically SumData    You will need to either    Make the called member static also   static void setTextboxText int result           Write static logic for setTextboxText           This may require a static singleton instance of Form1     Create an instance of Form1 within the calling method   private static void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             Form1 frm1   new Form1        frm1 setTextboxText result       Passing in an instance of Form1 would be an option also  Make the calling method a non-static instance method  of Form1    private void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             setTextboxText result        More info about this error can be found on MSDN

User · Answer

You start a thread which runs the static method SumData  However  SumData calls SetTextboxText which isn t static  Thus you need an instance of your form to call SetTextboxText

User · Answer

From my looking you give a null value to a textbox and return in a ToString   as it is a static method  You can replace it with  Convert ToString   that can enable null value

User · Answer

Your method must be static   static void setTextboxText int result        if  this InvokeRequired                this Invoke new IntDelegate SetTextboxTextSafe   new object     result                else               SetTextboxTextSafe result

User · Answer

You start a thread which runs the static method SumData  However  SumData calls SetTextboxText which isn t static  Thus you need an instance of your form to call SetTextboxText

User · Answer

For this case  where you want to get a Control of a Form and are receiving this error  then I have a little bypass for you   Go to your Program cs and change  Application Run new Form1       to  public static Form1 form1   new Form1       Place this var out of the constructor Application Run form1     Now you can access a control with  Program form1  lt Your control gt    Also  Don t forget to set your Control-Access-Level to Public   And yes I know  this answer does not fit to the question caller  but it fits to googlers who have this specific issue with controls

User · Answer

You start a thread which runs the static method SumData  However  SumData calls SetTextboxText which isn t static  Thus you need an instance of your form to call SetTextboxText

User · Answer

It looks like you are calling a non static member  a property or method  specifically setTextboxText  from a static method  specifically SumData    You will need to either    Make the called member static also   static void setTextboxText int result           Write static logic for setTextboxText           This may require a static singleton instance of Form1     Create an instance of Form1 within the calling method   private static void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             Form1 frm1   new Form1        frm1 setTextboxText result       Passing in an instance of Form1 would be an option also  Make the calling method a non-static instance method  of Form1    private void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             setTextboxText result        More info about this error can be found on MSDN

User · Answer

You start a thread which runs the static method SumData  However  SumData calls SetTextboxText which isn t static  Thus you need an instance of your form to call SetTextboxText

User · Answer

For this case  where you want to get a Control of a Form and are receiving this error  then I have a little bypass for you   Go to your Program cs and change  Application Run new Form1       to  public static Form1 form1   new Form1       Place this var out of the constructor Application Run form1     Now you can access a control with  Program form1  lt Your control gt    Also  Don t forget to set your Control-Access-Level to Public   And yes I know  this answer does not fit to the question caller  but it fits to googlers who have this specific issue with controls

User · Answer

I actually got this error because I was checking InnerHtml for some content that was generated dynamically  - i e  a control that is runat server   To solve this I had to remove the  static  keyword on my method  and it ran fine

User · Answer

It looks like you are calling a non static member  a property or method  specifically setTextboxText  from a static method  specifically SumData    You will need to either    Make the called member static also   static void setTextboxText int result           Write static logic for setTextboxText           This may require a static singleton instance of Form1     Create an instance of Form1 within the calling method   private static void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             Form1 frm1   new Form1        frm1 setTextboxText result       Passing in an instance of Form1 would be an option also  Make the calling method a non-static instance method  of Form1    private void SumData object state        int result   0        int   icount    int   state      int icount    int state       for  int i   icount  i  gt  0  i--                result    i          System Threading Thread Sleep 1000             setTextboxText result        More info about this error can be found on MSDN

User · Answer

I actually got this error because I was checking InnerHtml for some content that was generated dynamically  - i e  a control that is runat server   To solve this I had to remove the  static  keyword on my method  and it ran fine

User · Answer

Credit to  COOLGAMETUBE for tipping me off to what ended up working for me   His idea was good but I had a problem when Application SetCompatibleTextRenderingDefault was called after the form was already created   So with a little change  this is working for me    static class Program       public static Form1 form1       new Form1       Place this var out of the constructor           lt summary gt          The main entry point for the application           lt  summary gt       STAThread      static void Main                 Application EnableVisualStyles            Application SetCompatibleTextRenderingDefault false           Application Run form1   new Form1

[c#] CS0120: An object reference is required for the nonstatic field, method, or property 'foo'

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